1. Field of the Invention
This invention relates to a biochemical analysis apparatus which spots a sample liquid such as blood, serum, urine or the like on a dry-type frameless chemical analysis film having thereon a reagent layer (spreading layer) whose optical density changes by chemical reaction, immunoreaction, or the like with a specific biochemical component contained in the sample liquid and determines the concentration of the specific biochemical component in the sample liquid by measuring the optical density of the film.
2. Description of the Prior Art
There has been put into practice a biochemical analysis apparatus using a dry-type chemical analysis film with which a specific component contained in a sample liquid can be quantified through a droplet of the sample liquid spotted on the slide. When chemical components or the like contained in a sample liquid is analyzed using such a dry-type chemical analysis film, a droplet of the sample liquid is spotted on the slide and is held at a constant temperature for a predetermined time (incubation) in an incubator so that coloring reaction occurs, and the optical density of the color formed by the coloring reaction is optically measured. That is, measuring light containing a wavelength which is pre-selected according to the combination of the component to be analyzed and the reagent contained in the reagent layer of the film is projected onto the film and the optical density of the film is measured. Then the component to be analyzed is quantified on the basis of the optical density using a calibration curve which represents the relation between the concentration of the biochemical component and the optical density.
The chemical analysis film is generally composed of a base film of plastic or the like and a reagent layer and a spreading layer formed on the base film and is conventionally generally provided with a plastic frame which holds the chemical analysis film flat which is apt to warp into a roof tile shape when it dries.
The chemical analysis films are transferred to an incubator one by one after spotted with a sample liquid. Transfer of the chemical analysis slides can be done, for instance, by a reciprocating claw member as disclosed in U.S. Pat. Nos. 4,296,069 and 4,568,519 and the like. The frame facilitates transfer of the chemical analysis film.
However, the frame increases the volume of the chemical analysis film and results in increase in the size of various parts handling the film such as cells in the incubator for incubating the chemical analysis films. Thus the frame of the chemical analysis film is obstructive to reducing the size of the biochemical analysis apparatus and at the same time reduces the film accommodating capacity of the incubator, which obstructs increase in handling capability of the overall biochemical analysis apparatus.
An attempt to use a dry-type chemical analysis film without frame (will be referred to as "frameless chemical analysis film", hereinbelow) will encounter the following difficulties. That is, in order to automate the analysis, the frameless chemical analysis film must be surely transferred to the incubator and incubated therein. Though the frameless chemical analysis film is apt to warp into a roof tile shape when it dries as described above and the curvature of the warp changes in response to spotting of the sample liquid, the sample liquid must be precisely spotted on the curled frameless chemical analysis film and the film must be transferred to the incubator without touching the sample liquid thereon and the optical density must be measured with the film held flat and tightly enclosed.
That is, when the optical density is measured with some films curled and some films flat, measuring errors are produced. Further increase in temperature during heating differs and progressing rate of coloring reaction varies according to the curvature of the chemical analysis film, which can result in measuring errors. Accordingly, measurement of the optical density must be effected with the films held flat in the incubator. Further when a part of the film transfer means is in contact with the sample liquid during transfer of the films spotted with the sample liquid, the sample liquid adhering to the film transfer means can contaminate the reagent layer on the next chemical analysis film and adversely affect the accuracy of the analysis.
Further when the film transfer means is arranged to hold the film under suction on the bottom side (the side opposite to the reagent layer) and to insert the film into cell in the incubator, the incubator must be provided with a passage through which the suction member goes in the incubator, which makes it difficult to seal the film in the cell during incubation. When the film is not tightly enclosed, the sample liquid can evaporate and the vapor can contaminate other sample liquid, which can adversely affect the accuracy of the analysis.
Further when a transfer mechanism for taking out the chemical analysis slide or the frameless chemical analysis film from a film supplier and transferring it to the incubator (during the transfer, a sample liquid is spotted on the film or the slide) is provided between the film supplier and the incubator to transfer the film or the slide along a linear path, the space between the supplier and the incubator must be large, which increases the overall size of the chemical analysis apparatus.